Linear motor with three magnets and a coil carrier having multiple winding areas with each area having a section of a coil wound with one continuous wire, or separate coils respectively wound around each area with all coils wound in the same direction

ABSTRACT

A linear motor includes an assembly of three magnets in series coaxially affixed inside of a housing, which results in an air gap therebetween, wherein the assembly includes a middle magnet whose direction of magnetization is opposite to that of the rest of the magnets. A first embodiment of the motor includes a coil carrier having a single electrical coil of two sections wound in the same direction and positioned into the corresponding two winding areas. The carrier is movably positioned into the air gap and further surrounds the assembly, thereby moving along an axial direction of the motor. A second embodiment includes two coils that are wound in a same direction with the respective separated wires and positioned into the respective two winding areas of the coil carrier.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional patentapplication Ser. No. 61/398,698 filed on Jun. 29, 2010.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of linear motors whichinclude a coil surrounding a magnet assembly.

2. Description of the Prior Art

U.S. Pat. No. 5,345,206 issued to Anthony C. Morcos on Sep. 6, 1994 andassigned to BEI Electronics, Inc. discloses a cylindrically-symmetricalmoving coil linear actuator.

The actuator utilizes axially-magnetized cylindrical magnets to provideflux-focused interleaved magnetic circuits. The actuator includes acylindrical shell that has a closed end and an open end. A magnetic coreis disposed within the shell to define an annular air gap between theshell and the core. The core includes a first set of axially-magnetizedcylindrical permanent magnets having a first direction of magnetizationand disposed adjacent the closed end of the shell. A second set ofpermanent magnets has a second direction of magnetization which isopposite to the first direction of magnetization and is disposedadjacent the open end of the shell.

A moving coil assembly is disposed with the annular air gap. The coilassembly includes a non-magnetic coil carrier. A first coil winding isformed on the coil carrier in proximity to a first set of magnets and iswound to have a first polarity. A second coil winding is formed on thecoil carrier in proximity to a second set of magnets and is wound tohave a second polarity opposite to the first polarity such that thefirst and second coil windings are wound in opposite directions.

The invention disclosed in U.S. Pat. No. 5,345,206 can be improved upon.Specifically, it is not necessary for the first and second coil windingswhich are wound to have the opposite polarities as disclosed in theinvention.

There is a significant need to provide a linear motor that will simplifythe motor structure and reduce cost in manufacturing, while maintainingthe same functionality of the motor.

SUMMARY OF THE INVENTION

A first embodiment of the present invention linear motor includes anassembly of magnets coaxially affixed inside of a housing, an air gapsituated between the magnets and the housing so that a coil carrierhaving a single electrical coil of two sections wound in a samedirection is movably positioned within the air gap and also surroundsthe assembly of magnets. The coil carrier moves along an axial directionof the motor when the coil carrier is driven by forces resulting from aninteraction of the magnets and the single electrical coil after it issupplied with electricity. The single electrical coil preferablyincludes an even number of multiple layers of coil windings, whereineach layer of the coil winding is comprised of first and second sectionsthat are separated by a central barrier positioned within the coilcarrier. The assembly includes proximal, middle and distal magnetsaffixed in series, wherein a direction of magnetization of the middlemagnet is opposite to the direction of magnetization of the proximal anddistal magnets.

The housing is formed in the shape of a cylindrical container includingan opened proximal end, a closed distal end, and a cylindrical wallbetween the proximal and distal ends.

The assembly of magnets is also in a cylindrical shape and preferablyhas three permanent magnets: distal, middle and proximal magnets affixedin series. The distal permanent magnet has a direction of magnetizationwhich is coaxially connected to a distal pole piece, wherein the distalpole piece has the shape of a cylindrical disk and is made of aferromagnetic material. The distal pole piece is coaxially connected toa middle permanent magnet having a direction of magnetization that isopposite to the direction of magnetization of the distal magnet. Themiddle magnet is coaxially attached to a middle pole piece made of theferromagnetic material. The middle pole piece again is coaxiallyconnected to a proximal magnet having a direction of magnetization whichis the same as that of the distal magnet, wherein the proximal magnet isfurther connected to a proximal pole piece made of the ferromagneticmaterial.

The coil carrier is formed in the shape of a cylindrical container whichis made of non-magnetic material. The carrier is comprised of a proximalend having an exterior transverse surface and central opening, an opendistal end, and a cylindrical wall that surrounds an interiorcylindrical opening, wherein the central opening of the proximal end isconnected to the interior cylindrical opening.

A transverse circular notch is positioned at the proximal end of thecarrier to thereby form a proximal circular barrier having an interiortransverse ring surface and a first groove crossing the barrier. At amiddle of the cylindrical wall of the carrier, there is a circularprotrusion which serves as a central barrier to include first and secondtransverse ring surfaces, and a second groove that is aligned with theaxial orientation of the carrier. At the distal end of the carrier thereis positioned a distal transverse flange, which serves as a distalbarrier. Therefore, the proximal barrier and central barrier form afirst winding area for winding a first section of the single electricalcoil. The central barrier and distal barrier form a second winding areafor winding a second section of the coil.

For winding the single electrical coil, the coil winding starts with afirst layer of coil wound on the coil carrier that also serves as asupporter and locking device for the coil. In the winding process, afirst end of a wire is positioned inside of the notch, and then bent ata 90 degree angle to pass through the first groove of the proximalbarrier. The wire is then bent into another 90 degree angle to againcontact the interior transverse ring surface of the proximal barrier forwinding the coil in a given direction which can be either clockwise orcounter-clockwise.

A first coil layer winding is completed when the coil is wound in onedirection such as the clockwise direction, going from the interiortransverse ring surface of the proximal barrier until it reaches thefirst transverse ring surface of the central barrier. When the wirecomes into contact with the first transverse ring surface of the centralbarrier, the wire is bent to pass through a second groove in the centralbarrier, and then bent another 90 degrees to contact the secondtransverse ring surface of the central barrier, so that the coilcontinues to be wound in the same clockwise direction and longitudinaldirection towards the distal barrier.

When the wire comes into contact with the interior transverse ringsurface of the distal barrier, the first layer of winding is completed.A second layer is wound in the same clockwise direction but travels inthe opposite axial direction as compared with the first winding layer.

When the second winding layer encounters the second transverse ringsurface of the central barrier, it is bent to extend through the grooveand the winding continues from the first transverse ring surface of thecentral barrier to the interior transverse surface of the proximalbarrier. The second layer of winding is positioned above the first layerof winding. Multiple successive layers are wound in the same manner.

The advantages of the single electrical coil from the first embodimentof the present invention are (1) a single wire is used to form the coil,which eliminates a necessary wire connection between first and secondcoil windings; (2) the first and second ends of the single electricalcoil of the present invention are both positioned at the proximal end ofthe coil carrier which makes it easier to manufacture; (3) the singlecoil having the even numbered layers of the coil windings causes areduction of the width of the air gap which significantly increases theamount of force the motor can supply; and (4) the single coil has auniform polarity when is supplied with electricity.

A second embodiment of the present invention linear motor is similar tothe first embodiment, except for having first and second coils that arepositioned in the corresponding first and second winding areas and woundin the same direction with the respective separated first and secondwires. Therefore, for positioning two sections of the second wire thatare connected to the respective first and second ends of the secondcoil, the second embodiment has a wider air gap as compared with that ofthe first embodiment.

Variations of the respective embodiments result in a single electricalcoil having multiple sections of the coil windings wound in the samedirection, or multiple coils wound in the same direction according tomultiple winding areas of the coil carrier for the present inventionlinear motor.

Further novel features and other objects of the present invention willbecome apparent from the following detailed description and discussion.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring particularly to the drawings for the purpose of illustrationonly and not limitation, there is illustrated:

FIG. 1 is a perspective view of a linear motor from a first embodimentof the present invention, illustrating a movable coil carrier which ismoved forwardly away from a housing of the motor along an axialdirection of the motor;

FIG. 2A is a longitudinal cross-section view of the linear motor shownin FIG. 1;

FIG. 2B is a longitudinal cross-section view of the linear motor fromthe first embodiment of the present invention, which illustrates themovable coil carrier when it is moved backward to a position inside ofthe housing;

FIG. 2C is a longitudinal cross-sectional view of the linear motor,which illustrates the magnetic flux paths of the motor when the linearmotor is in the position illustrated in FIG. 2B;

FIG. 3A is a perspective view of the coil carrier for the linear motorfrom the first embodiment of the present invention;

FIG. 3B is a front view of the coil carrier illustrated in FIG. 3A;

FIG. 4 is a perspective view of a coil carrier with two wound coils inthe same winding direction from a second embodiment of the presentinvention;

FIG. 5 is a longitudinal cross-sectional view of a linear motor from thesecond embodiment of the present invention, illustrating a movable coilcarrier which is moved forwardly away from a housing of the motor alongan axial direction of the motor;

FIG. 6A is a perspective view of the coil carrier of the linear motorfrom the second embodiment of the present invention; and

FIG. 6B is a front view of the coil carrier illustrated in FIG. 6A.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Although specific embodiments of the present invention will now bedescribed with reference to the drawings, it should be understood thatsuch embodiments are by way of example only and merely illustrative ofbut a small number of the many possible specific embodiments which canrepresent applications of the principles of the present invention.Various changes and modifications obvious to one skilled in the art towhich the present invention pertains are deemed to be within the spirit,scope and contemplation of the present invention.

Referring to FIG. 1, there is illustrated first embodiment 10 of thepresent invention linear motor in a preferred cylindrical shape. Thefigure particularly illustrates that a movable coil carrier 24 of themotor moves forward along an axial direction of the motor and relativeto a housing 12 of the motor. In addition, the figure also shows thecoil carrier has a single electrical coil 22.

As further illustrated in FIG. 2A, the linear motor 10 includes themovable coil carrier 24 and an interior assembly 58 of magnets that isaffixed inside of the exterior housing 12. The housing has a shape of acylindrical container, and is made of a ferromagnetic material. Thehousing is comprised of an open proximal end 14, a closed distal end 16that may include a central threaded opening 18, and a cylindrical wall20 between the proximal and distal ends.

The magnet assembly 58 is also in a cylindrical shape and preferably hasthree permanent magnets: distal, middle and proximal magnets affixed inseries. The distal permanent magnet 60 has first and second magneticpoles 62 and 64, which second magnetic pole 64 is coaxially connected toa distal pole piece 66 that is in the shape of a cylindrical disk andmade of a ferromagnetic material. The distal pole piece 66 is coaxiallyconnected to a middle permanent magnet 68 having third and fourthmagnetic poles 70 and 72. The middle magnet at its third pole 70 iscoaxially attached to a middle pole piece 74 made of the ferromagneticmaterial. The middle pole piece again is coaxially connected to aproximal magnet 76 having fifth and sixth magnetic poles 78 and 80,wherein the proximal magnet at the sixth magnetic pole 80 is connectedto a proximal pole piece 82 made of ferromagnetic material.

Referring to FIG. 2A, there is illustrated that the first and secondpoles 62 and 64 determine a direction of the magnetic field ormagnetization of the distal magnet 60. Similarly, the fifth and sixthpoles 78 and 80 determine the direction of magnetization of the proximalmagnet 76. The distal and proximal magnets have the same direction ofmagnetization. However, a direction of the magnetic field of the middlemagnet 68 is opposite to the direction of the magnetization of therespective distal and proximal magnets. The third and fourth poles 70and 72 determine the direction of magnetization 68 of the middlepermanent magnet which is the direction opposite to the distal andproximal magnets. It will be appreciated that with this design of themagnet assembly, the linear motor 10 will output strong axial forceswhen its coil is supplied with direct electric current.

As further illustrated in FIGS. 1 and 2B, the assembly of the magnets iscoaxially affixed inside of the housing, wherein the proximal pole piece82 is aligned with the opened proximal end 14 of the housing, and thedistal magnet 60 is connected to a center of an interior surface of theclosed distal end 16 of the housing. It will be appreciated that thedistal magnet 60 can be affixed to the distal end of the housing byadhesive, or it can be mechanically affixed by application of fastenerssuch as a screw. Affixed in this way, a circular air gap 25 is formedbetween the wall 20 of the housing and assembly 58 to thereby provideroom for the movable coil carrier 24, which is movably positioned tosurround the magnet assembly 58 in a back and forth axial movement alongthe axial direction of the motor 10.

Referring to FIGS. 2A, 3A and 3B, the coil carrier 24 or bobbin isillustrated to have a shape of a cylindrical container, which is made ofa non-magnetic material. The carrier 24 is comprised of a proximal end26 having an exterior transverse surface 28 and central opening 27, anopened distal end 56, and a cylindrical wall 54 that surrounds aninterior cylindrical opening 57, wherein the central opening 27 isconnected to the interior cylindrical opening 57.

As further illustrated, a transverse circular notch 32 is positioned atthe proximal end 26. This forms a proximal circular barrier 34, whichhas an interior transverse ring surface 35 and a first groove 30crossing the barrier.

A circular protrusion which serves as a central barrier 40 is positionedat a middle of the cylindrical wall 54 of the carrier. The centralbarrier 40 has a width which is significantly wider than that of theproximal barrier 34. The central barrier is illustrated to include firstand second transverse ring surfaces 42 and 46, and a second groove 44that is aligned with the axial orientation of the carrier. In addition,a distal transverse flange 50 is positioned at the distal end 56 of thecoil carrier, which serves as a distal barrier.

Referring to FIGS. 2A, 2B, 3A and 3B again, the proximal barrier 34 andcentral barrier 40 are illustrated to form a first winding area 38 forwinding a first section 88 of the single coil of the present invention.The central barrier 40 and distal flange 50 form a second winding area48 for winding a second section 91 of the single coil.

In addition, as illustrated in FIG. 2B, the first winding area 38 has awidth which is equal to a width of the proximal permanent magnet 76 thatis combined with a width of the proximal pole piece 82. Similarly, thesecond winding area 48 has a width which is equal to a width of thedistal permanent magnet 60 that is combined with a width of the distalpole piece 66. It will be appreciated that according to a preferredembodiment of the coil carrier, the first winding area has a width whichis the same as that of the second winding area.

When winding the single electrical coil of the present invention, onecan start to wind a first layer of the coil around the coil carrierwhich also serves as a supporter and locking device for the singleelectrical coil. In a process of winding the electrical coil, forexample, as illustrated in FIG. 1, a first end 86 of a wire 85 ispositioned inside of the notch 32, and then bent at a 90 degree angle topass through the first groove 30 of the proximal barrier 34. It will beappreciated that the wire is then bent another 90 degrees to againcontact the interior transverse ring surface 35 of the proximal barrierfor winding the coil following a given direction such as clockwise. Inthis setting the first groove 30 serves as a locking device which locksthe first end 86 of the wire so that it can tightly wind a first layer89 of the single electrical coil in the first section 88.

The first layer 89 of the first section 88 of the single electrical coilis wound by continuing to wind the coil in the clockwise direction and alongitudinal direction towards the first transverse ring surface 42 ofthe central barrier. When the wire comes into contact with the surface42, the wire is first bent to pass through the second groove 44 of thecentral barrier 40, and then bent at another 90 degree angle to contactthe second transverse ring surface 46 of the central barrier. In thissetting, the second groove 44 serves as a room for positioning a section90 of the wire illustrated in FIG. 2A, and a locking device so that afirst layer 89 of the single coil in the second section 91 can betightly wound, wherein the coil winding is simultaneously wound in thesame clockwise direction and longitudinal direction towards the distalflange 50.

When the wire comes into contact with the interior transverse ringsurface 52 of the distal flange, it completes the winding of the firstlayer 89 of the single electrical coil in the second section 91. Then, asecond layer 92 of winding in the second section 91 is positioned abovethe first layer and further positioned to contact the first layer 89 ofthe single electrical coil. Following the same clockwise direction and adirection towards the central barrier 40, winding of the second layer 92of the single coil in the second section 91 is completed when the wirecomes into contact with the second transverse ring surface 46. The wireis then bent to pass through the second groove 44, wherein a section 94of the wire is illustrated in FIG. 2A to be positioned inside of thesecond groove. The wire is further bent to enter into a first windingarea 38 for winding a second layer 92 of the single coil in the firstsection 88 in a similar fashion as the winding of the second layer inthe second section. It will be appreciated that the coil windings of therespective first and second layers have the same electromagneticpolarity when supplied with electricity since the first and secondlayers of the coil windings are wound in the same clockwise direction.

The single electrical coil is completely wound when an even number ofmultiple layers of the coil windings in the first and second sectionsare completed in accordance with a required number of coil windings fora given linear motor. Therefore, a second end 95 of the wire is bent topass through the first groove 30, and further bent to be positionedinside of the notch 32, which is illustrated in FIG. 1. In thissituation, the second end 95 of the wire is positioned above the firstend 86 of the wire.

It will be appreciated that the single electrical coil can also be woundin a counterclockwise direction.

The advantages of the single electrical coil of the present inventionlinear motor include that a single continuous wire is used to form thecoil having two sections, which eliminates a necessary internal wire forrouting the wires from the second coil winding over the first coilwinding and into termination area 32 to then be connected to the wiresfrom the first coil winding. This is advantageous since by eliminatingthe internal connecting wire having a defined diameter that occupies acorresponding air space facilitating a reduced width of the circular airgap 25 of the present invention, which results in increase of forces ofthe linear motor.

In addition, the first and second ends 86 and 95 of the singleelectrical coil of the present invention are both positioned at theproximal end of the coil carrier, which is also easier to manufacture.Furthermore, the present invention single coil has uniform polarity whenis supplied with electricity, as compared with two opposite polaritiesfrom the existing technologies.

Referring to FIG. 2B, there is illustrated longitudinal cross-section ofthe present invention linear motor 10, wherein the coil carriercompletes a backward movement so that the distal barrier 50 of thecarrier is positioned adjacent the distal end 16 of the housing.

It will be appreciated that the forward and backward moving abilities ofthe coil carrier 24, which are illustrated in the respective FIGS. 1, 2Aand 2B, are relative to the housing 12 that is assumed to be in astationary condition. For example, the housing is affixed to a substratethat is stationary. Therefore, the movable coil carrier in its forwardand backward movement will provide the respective forward and backwardforces to an object, for example which is connected to the head of thecarrier, so that the object is then driven to have the correspondingforward and backward movement, as compared with the movement of thepresent invention linear motor. Alternatively, the coil carrier 24 canbe set at a stationary condition, so that the housing 12 can have aforward or a backward movement relative to the coil carrier. In thissituation, the movable housing will provide forces to an object that isconnected to the housing of the present invention linear motor.

The theory of how the motor works is as follows:

When a wire carrying current is placed in a magnetic field, a force willact upon it. The magnitude of this force is a function of magnetic fluxdensity, the current and the orientation between the two.

In the case of a traditional single permanent magnet/coil pair wherein apole piece is connected to the magnet, a magnetic flux of the permanentmagnet is directed by the pole piece to cross a small air gap betweenthe edge of the pole piece and wall of a housing of the motor.

The electrical current within the portion of the coil that crosses thismagnetic flux generates a force in the axial direction of the motor. Byreversing the direction of the current or the direction of the magneticfield, the force will be reversed.

In the case of the present invention linear motor, a first arrangementof the distal magnet 60, distal pole piece 66 and second section 91 ofthe single coil creates the above illustrated force according to amagnetic flux 84 illustrated in FIG. 2C, which is determined by themagnetic poles 62 and 64. As illustrated, the magnetic flux 84 of thefirst arrangement is symmetric relative to a symmetric axis 99 of themotor. The flux 84 completes a loop consisting of the distal magnet 60,the distal end 16 and wall 20 of the housing, the air gap 25 whosemajority is occupied by the second section 91 of the single coil and thedistal pole piece 66.

In addition, a second arrangement of the proximal magnet 76, proximalpole piece 82 and first section 88 of the single coil has the samefunction as that of the first arrangement. The current that passesthrough the first section 88 of the single coil crosses the magneticflux 79 which in turn creates an axial force, wherein the flux 79completes a loop consisting of the proximal magnet 76, middle pole piece74, air gap 25 whose majority is occupied by the central barrier 40 ofthe coil carrier, wall 20 of the housing, air gap 25 whose majority isoccupied by the first section 88 of the coil, and proximal pole piece82.

Since in the first and second arrangements the current flows in the samedirection and the magnetic flux that crosses the respective first andsecond sections 88 and 91 of the single coil have the same direction,the above illustrated two forces will also be in the same direction,therefore they add up. However, it also brings a possibility of a smallaxial leakage of the magnetic flux between the distal and proximalmagnets 60 and 76, wherein the possible leakage of the magnetic fluxcould reduce the flux density crossing the respective first and secondsections of the single coil to thereby reduce forces of the motor.

Therefore, it is advantageous for the present invention to add themiddle magnet 68, since the middle magnet minimizes an effect of theaxial leakage between the distal and proximal magnets due to itsopposing magnetic flux 87 as compared with the respective flux 84 and79. Additionally it will add flux to the flux of the magnet assembly, asillustrated that a direction of the magnetic flux of the middle magnet68 in the middle pole piece 74 is consistent with that of the proximalmagnet 76 in the same pole piece. Similarly, a direction of the magneticflux of the middle magnet 68 in the distal pole piece 66 is consistentwith that of the distal magnet 60 in the same pole piece. Accordingly,it increases forces of the present invention linear motor having theassembly of three magnets.

As compared with the above illustrated single coil having the evennumbered layers of the coil windings, the single coil can also be woundto have an odd number of multiple layers of the coil windings. Forexample, referring to FIG. 2A, an odd numbered layer of the coilwindings end adjacent to the distal end 50 of the coil carrier, the endof the wire is positioned inside of the notch 32, after a section of thewire is pulled to pass the second and first grooves 44 and 30. However,this option is less preferred, since it requires an additional air spacefor positioning the section of the wire, which increases the width ofthe air gap 25 between the assembly 58 of the magnets and wall 20 of thehousing, thereby decreasing forces of the linear motor.

It will be appreciated that from the above illustrated single coilhaving two sections of the coil windings, it reveals the spirit andscope of the present invention linear motor according to the firstembodiment, wherein the single coil can have multiple sections of thecoil windings wound in a same direction when applying a continuous wire.Accordingly, the coil carrier has the corresponding multiple windingareas. In addition, as compared with the single coil configurationillustrated in the first embodiment 10, the present invention linearmotor has a second embodiment 109, which has a dual coil configuration,wherein two coils are wound in the same direction with the respectiveseparated wires, as illustrated in FIG. 5.

The second embodiment 109 of the present invention linear motor includesfirst and second coils 187 and 190, which are wound in the samedirection and by the respective separated wires 184 and 185, and arealso illustrated in FIG. 4. Because of this structural configuration, itresults in a coil carrier 121, circular air gap 123 between a housing111 and magnet assembly 158, and two coils, which are different fromthose of the first embodiment 10.

A disclosure will not be repeated for structural features of the secondembodiment 109, which are identical to those of the first embodiment.These structural features are designated with three-digit numerals.

Referring to FIGS. 6A and 6B, there is illustrated coil carrier 121 ofthe second embodiment. It will be appreciated that, the difference ofthe coil carrier 121 is absence of the second groove 44 in the axialorientation, as compared with the coil carrier 24 of the firstembodiment. Instead, there is a second notch 145 positioned on thesecond ring surface 146. Therefore, as illustrated in FIG. 4, the firstcoil 187 is wound in a first winding area 138 when applying the firstwire 184 having a first end 186 and second end 188 in a similar fashionas disclosed for the first section 88 of the single coil in the firstembodiment 10. The difference is that the first coil 187 is wound backand forth in the first wound area 138 in the same clockwise direction.

The second coil 190 is wound in a second wind area 148 when applying thesecond wire 185 having a first end 189 and second end 191 in a similarfashion as disclosed for the second section 91 of the single coil 22 inthe first embodiment. The difference is that the second coil 190 iswound back and forth in the second winding area 148 in the sameclockwise direction, in addition to first and second ends 189 and 191 ofthe wire connected to the corresponding sections of the wire 185 thatmust be positioned above an exterior layer of the first coil 187, afterthe first and second ends pass the second notch 145. In this setting,the second notch serves as a locking device to lock the correspondingsections of the wire 185 at positions where the wire is wound into thesecond winding area 148.

It will be appreciated that because of presence of the first and secondends of the second coil 190, there is a need for an additional room inthe circular air gap 123 of the housing to position the two endsconnected to the corresponding sections of the wire 185. Foraccommodating this requirement, a diameter of a distal end 117 of thehousing 111 of the second embodiment is larger than that of the distalend 16 of the first embodiment. This results in an enlarged width of theair gap 123 of the second embodiment, as compared with a width of theair gap 25 of the first embodiment. It will be further appreciated that,as disclosed above, the enlarged width of the air gap cause forces ofthe linear motor in the second embodiment 109 to be less than those ofthe first embodiment 10.

It will be further appreciated that, from the above illustrated twocoils wound in the same direction, either clockwise orcounter-clockwise, with the respective separated wires, it reveals thespirit and scope of the present invention linear motor according to thesecond embodiment, which includes multiple coils wound in the samedirection when applying the respective separated wires.

It will be additionally appreciated that, the linear motor of thepresent invention can have any symmetric shapes regarding its transversecross section relative to the symmetric axis 99 although the cylindricalmotor having a round cross section is disclosed above as the preferableembodiments.

Of course the present invention is not intended to be restricted to anyparticular form or arrangement, or any specific embodiment, or anyspecific use, disclosed herein, since the same may be modified invarious particulars or relations without departing from the spirit orscope of the claimed invention hereinabove shown and described of whichthe apparatus or method shown is intended only for illustration anddisclosure of an operative embodiment and not to show all of the variousforms or modifications in which this invention might be embodied oroperated.

The invention claimed is:
 1. A linear motor, comprising: a. a housinghaving an exterior wall to form an interior chamber, the housing havingan open proximal end and a closed distal end, a movable, bobbin at leastpartially within the chamber and movable in a back and forth axialdirection from the distal end of the housing to and through the openproximal end of the housing; b. a distal axially magnetized permanentmagnet located within and adjacent to distal end of the housing, thedistal permanent magnet having a first magnetic pole and a secondmagnetic pole, the distal magnet coaxially connected at a location ofits second magnetic pole to a first side of a distal pole piece made offerromagnetic material; c. a middle axially magnetized permanent magnetlocated within the housing and aligned with the distal magnet, themiddle permanent magnet having a third magnetic pole and a fourthmagnetic pole, the middle magnet coaxially affixed at a location of itsthird magnetic pole to a second side of the distal pole piece andaffixed at a location of its fourth magnetic pole to a first side of amiddle pole piece made of ferromagnetic material; d. a proximal axiallymagnetized permanent magnet located within the housing and aligned withthe middle magnet, the proximal permanent magnet having a fifth magneticpole and a sixth magnetic pole, the proximal magnet affixed at alocation of its fifth magnetic pole to a second side of the middle polepiece and affixed at a location of its sixth magnetic pole to a firstside of a proximal pole piece made of ferromagnetic material; e. thefirst and second poles of the distal permanent magnet determine thedirection of magnetization of the distal permanent magnet, the fifth andsixth magnetic poles of the proximal permanent magnet determine thedirection of magnetization of the proximal permanent magnet, and thedistal and proximal permanent magnets have a same direction ofmagnetization, the third and fourth magnetic poles of the middlepermanent magnet determine the direction of magnetization of the middlepermanent magnet which is opposite to the direction of magnetization ofthe distal and proximal permanent magnets; f. the distal permanentmagnet affixed at a location of its first magnetic pole to an interiorsurface of the distal end of the housing and a second side of theproximal pole piece is aligned with the open proximal end of thehousing, a circumferential air gap of a given radial width formedbetween an interior circumferential wall of the housing and an alignedmagnet assembly of the distal, middle, and proximal magnets and distal,middle and proximal pole pieces; g. the bobbin having a cylindrical wallwith an exterior surface and an interior surface surrounding a hollowinterior chamber, three spaced apart barriers formed on and extendingradially above the exterior surface of the cylindrical wall including aproximal barrier with a longitudinal groove, a middle barrier with analigned longitudinal groove and a distal barrier, a first winding areaformed on the cylindrical wall of the bobbin between the proximalbarrier and the middle barrier and a second winding area formed on thecylindrical wall of the bobbin between the middle barrier and the distalbarrier; h. a single electrical wire wound on the bobbin, the singleelectrical wire having a first end retained by the proximal barrier andextending through the longitudinal groove of the proximal barrier andwound around the first winding area of the cylindrical wall of thebobbin until it reaches the middle barrier, the electrical wire passingthrough the longitudinal groove in the middle barrier and wound aroundthe second winding area of the cylindrical wall of the bobbin until theelectrical wire reaches the distal barrier to complete a first windinglayer, at least a second winding layer in the second winding area formedby winding the electrical wire in the same direction and going from thedistal barrier to the middle barrier, passing through the groove in themiddle barrier and wound within the first winding area in the samedirection until it reaches the proximal barrier completing the secondwinding layer, a second end of the wire extends through the groove inthe proximal barrier to rest adjacent the first end of the electricalwire; i. the bobbin movably retained in the housing so that the hollowinterior chamber of the bobbin surrounds the magnet assembly andbarriers of the bobbin reside within the gap in the housing between themagnet assembly and the interior circumferential wall of the housing,the central barrier of the bobbin being of sufficient width so that whenwindings on the bobbin are entirely within the housing, the electricalwire wound on the first winding area and the electrical wire wound onthe second winding area do not encircle the middle permanent magnet andwhen the bobbin is in its fully extended condition that is partially outof the housing, the electrical wire wound on the first winding area andthe electrical wire wound on the second winding area do not encircle theproximal permanent magnet; and j. a source of electrical currentconnected to the wire interacts with a magnetic field created by thepermanent magnet so that the bobbin moves axially relative to thehousing so that the electrical wire of first and second winding areasare entirely within the housing in a first condition and the wire of thefirst winding area is out of the housing while the wire of the secondwinding area is in the housing in a second condition, use of a singlewire reducing the radial width of the air gap between the bobbin and theinterior circumferential wall of the housing so that an increased forceis generated by the relative movement of the bobbin and the housing. 2.The linear motor in accordance with claim 1 wherein the bobbin isaffixed to a stationary object and the housing moves relative to thebobbin when the source of electrical current is applied to the wire. 3.The linear motor in accordance with claim 1 wherein the housing isaffixed to a stationary object and the bobbin moves relative to thehousing.
 4. The linear motor in accordance with claim 1 wherein theproximal barrier further comprises a transverse circular notch to retainthe first and second end of the wire.
 5. The linear motor in accordancewith claim 1 further comprising a multiplicity of windings of the wirein the first winding area and the second winding area.
 6. A linearmotor, comprising: a. a housing having an exterior wall to form aninterior chamber, the housing having an open proximal end and a closeddistal end, a movable bobbin at least partially within the interiorchamber and movable in a back and forth axial direction from the distalend of the housing to and through the open proximal end of the housing;b. a magnet assembly comprising a distal magnet, a middle magnet, and aproximal magnet, a distal pole piece between the distal magnet and themiddle magnet, a middle pole piece between the middle magnet and theproximal magnet, a proximal pole piece located adjacent to the proximalmagnet at a location not touching the middle pole piece, the distalmagnet affixed to an interior surface of the distal end of the housingso that the magnet assembly is retained within the interior chamber ofthe housing with a circumferential air gap of a given radial widthbetween the interior circumferential surface of the housing and themagnet assembly, a direction of magnetization of the distal and proximalmagnets being the same and the direction of the magnetization of themiddle magnet being opposite to the direction of magnetization of thedistal and proximal magnets; c. the bobbin having a cylindrical wallwith an exterior surface and an interior surface surrounding a hollowinterior chamber, three spaced apart barriers formed on and extendingradially above the exterior surface of the cylindrical wall including aproximal barrier with a longitudinal groove, a middle barrier with analigned longitudinal groove and a distal barrier, a first winding areaformed on the cylindrical wall of the bobbin between the proximalbarrier and the middle barrier and a second winding area formed on thecylindrical wall of the bobbin between the middle barrier and the distalbarrier; d. a single electrical wire wound on the bobbin, the singleelectrical wire having a first end retained by the proximal barrier andextending through the longitudinal groove of the proximal barrier andwound around the first winding area of the cylindrical wall of thebobbin until the wire reaches the middle barrier, the electrical wirepassing through the longitudinal groove in the middle barrier and woundaround the second winding area of the cylindrical wall of the bobbinuntil the electrical wire reaches the distal barrier to complete a firstwinding layer, at least a second winding layer formed by winding theelectrical wire in the same direction and going from the distal barrierto the middle barrier, passing through the groove in the middle barrierand wound in the same direction until it reaches the proximal barrier tocomplete the second winding layer, a second end of the wire extendsthrough the groove in the proximal barrier to rest adjacent the firstend of the electrical wire; e. the bobbin movably retained in thehousing so that the hollow interior chamber of the bobbin surrounds themagnet assembly and barriers of the bobbin reside within the gap in thehousing between the magnet assembly and the interior circumferentialwall of the housing, the central barrier of the bobbin being ofsufficient width so that when windings on the bobbin are entirely withinthe housing, the electrical wire wound on the first winding area and theelectrical wire wound on the second winding area do not encircle themiddle permanent magnet and when the bobbin is in its fully extendedcondition partially out of the housing, the electrical wire wound on thefirst winding area and the electrical wire wound on the second windingarea do not encircle the proximal permanent magnet; and f. a source ofelectrical current connected to the wire interacts with a magnetic fieldcreated by the permanent magnets so that the bobbin moves axiallyrelative to the housing so that the wire in the first and second windingareas are entirely within the housing in a first condition and theelectrical wire of the first winding area is out of the housing whilethe electrical wire of the second winding area is in the housing in asecond condition, use of a single wire reducing the radial width air gapbetween the bobbin and the interior circumferential wall of the housingso that an increased force is generated by the relative movement of thebobbin and the housing.
 7. The linear motor in accordance with claim 6wherein the distal magnet, middle magnet and proximal magnet are eachpermanent magnets.
 8. The linear motor in accordance with claim 6wherein the distal pole piece, middle pole piece and proximal pole pieceare each made of ferromagnetic material.
 9. The linear motor inaccordance with claim 6 wherein the bobbin is affixed to a stationaryobject and the housing moves relative to the bobbin when the source ofelectrical current is applied to the wire.
 10. The linear motor inaccordance with claim 6 wherein the housing is affixed to a stationaryobject and the bobbin moves relative to the housing.
 11. The linearmotor in accordance with claim 6 wherein the proximal barrier furthercomprises a transverse circular notch to retain the first and second endof the wire.
 12. The linear motor in accordance with claim 6 furthercomprising a multiplicity of windings of the wire in the first windingarea and the second winding area.
 13. A linear motor, comprising: a. ahousing having an exterior wall to form an interior chamber, the housinghaving an open proximal end and a closed distal end, a movable bobbin atleast partially within the chamber and movable in a back and forth axialdirection from the distal end of the housing to and through the openproximal end of the housing; b. a distal axially magnetized permanentmagnet located within and adjacent to the distal end of the housing, thedistal permanent magnet having a first magnetic pole and a secondmagnetic pole, the distal magnet coaxially connected at a location ofits second magnetic pole to a first side of a distal pole piece made offerromagnetic material; c. a middle axially magnetized permanent magnetlocated within the housing and aligned with the distal magnet, themiddle permanent magnet having a third magnetic pole and a fourthmagnetic pole, the middle magnet coaxially affixed at a location of itsthird magnetic pole to a second side of the distal pole piece andaffixed at a location of its fourth magnetic pole to a first side of amiddle pole piece made of ferromagnetic material; d. a proximal axiallymagnetized permanent magnet located within the housing and aligned withthe middle magnet, the proximal permanent magnet having a fifth magneticpole and a sixth magnetic pole, the proximal magnet affixed at alocation of its fifth magnetic pole to a second side of the middle polepiece and affixed at a location of its sixth magnetic pole to a firstside of a proximal pole piece made of ferromagnetic material; e. thefirst and second poles of the distal permanent magnet determine thedirection of magnetization of the distal permanent magnet, the fifth andsixth magnetic poles of the proximal permanent magnet determine thedirection of magnetization of the proximal permanent magnet, and thedistal and proximal permanent magnets have a same direction ofmagnetization, the third and fourth magnetic poles of the middlepermanent magnet determine the direction of magnetization of the middlepermanent magnet which is opposite to the direction of magnetization ofthe distal and proximal permanent magnets; f. the distal permanentmagnet affixed at a location of its first magnetic pole to an interiorsurface of the distal end of the housing and a second side of theproximal pole piece is aligned with the open proximal end of thehousing, a circumferential gap formed between an interiorcircumferential wall of the housing and an aligned magnet assembly ofthe distal, middle, and proximal magnets and distal, middle and proximalpole pieces; g. the bobbin having a cylindrical wall with an exteriorsurface and an interior surface surrounding a hollow interior chamber,three spaced apart barriers formed on and extending radially above theexterior surface of the cylindrical wall including a proximal barrierwith a longitudinal groove, a middle barrier with a notch and a distalbarrier, a first winding area formed on the cylindrical wall of thebobbin between the proximal barrier and the middle barrier and a secondwinding area formed on the cylindrical wall of the bobbin between themiddle barrier and the distal barrier; h. a first electrical wire woundon the bobbin, the first electrical wire having a first end retained bythe proximal barrier and extending through the longitudinal groove ofthe proximal barrier and wound around the first winding area of thecylindrical wall of the bobbin cylindrical wall until it reaches themiddle barrier, the first electrical wire wound in the same directionbut wound from the middle barrier to the proximal barrier, i. a secondend of the first electrical wire extends out of the groove in theproximal barrier; i. a second electrical wire wound on the bobbin, thesecond electrical wire having a first end retained by the proximalbarrier and extending over the windings of the first wire and retainedin the notch of the middle barrier and wound around the second windingarea of the cylindrical wall of the bobbin until the electrical wirereaches the distal barrier, and then extending over the first electricalwire with a second end extending through the groove in the proximalbarrier to rest adjacent the first end of the second electrical wire; j.the bobbin movably retained in the housing so that the hollow interiorchamber of the bobbin surrounds the magnet assembly and barriers of thebobbin reside within the gap in the housing between the magnet assemblyand the interior circumferential wall of the housing, the centralbarrier of the bobbin being of sufficient width so that when windings onthe bobbin are entirely within the housing, the first electrical wirewound on the first winding area and the second electrical wire wound onthe second winding area do not encircle the middle permanent magnet andwhen the bobbin is in its fully extended condition that is partially outof the housing, the first electrical wire wound on the first windingarea and the second electrical wire wound on the second winding area donot encircle the proximal permanent magnet; and k. a source ofelectrical current connected to the first and second wires interactswith the magnetic field created by the permanent magnets, thereby movingthe bobbin axially relative to the housing so that the first and secondwindings are entirely within the housing in a first condition and thefirst winding is out of the housing while the second winding is in thehousing in a second condition.
 14. The linear motor in accordance withclaim 13 wherein the bobbin is affixed to a stationary object and thehousing moves relative to the bobbin when the source of electricalcurrent is applied to the wire.
 15. The linear motor in accordance withclaim 13 wherein the housing is affixed to a stationary object and thebobbin moves relative to the housing.
 16. The linear motor in accordancewith claim 13 wherein the proximal barrier further comprises atransverse circular notch to retain the first and second end of thewire.
 17. The linear motor in accordance with claim 13 furthercomprising a multiplicity of windings of the wire in the first windingarea and the second winding area.
 18. A linear motor, comprising: a. ahousing having an exterior wall to form an interior chamber, the housinghaving an open proximal end and a closed distal end, a movable bobbin atleast partially within the interior chamber and movable in a back andforth axial direction from the distal end of the housing to and throughthe open proximal end of the housing; b. a magnet assembly comprising adistal magnet, a middle magnet, and a proximal magnet, a distal polepiece between the distal magnet and the middle magnet, a middle polepiece between the middle magnet and the proximal magnet, a proximal palepiece located adjacent to the proximal magnet at a location not touchingthe middle pole piece, the distal magnet affixed to an interior surfaceof the distal end of the housing so that the magnet assembly is retainedwithin the interior chamber of the housing with a circumferential airgap of a given radial width between the interior circumferential wall ofthe housing and the magnet assembly, a direction of magnetization of thedistal and proximal magnets being the same and the direction ofmagnetization of the middle magnet being opposite to the direction ofmagnetization of the distal and proximal magnets; c. the bobbin having acylindrical wall with an exterior surface and an interior surfacesurrounding a hollow interior chamber, three spaced apart barriersformed on and extending radially above the exterior surface of thecylindrical wall including a proximal barrier with a longitudinalgroove, a middle bather with a notch and a distal barrier, a firstwinding area formed on the bobbin cylindrical wall between the proximalbarrier and the middle barrier and a second winding area formed on thebobbin cylindrical wall between the middle barrier and the distalbarrier; d. a first electrical wire wound on the bobbin, the firstelectrical wire having a first end retained by the proximal barrier andextending through the longitudinal groove of the proximal barrier andwound around the first winding area of the cylindrical wall of thebobbin until it reaches the middle barrier, to form a first windinglayer, the first electrical wire continuously wound in the samedirection but wound from the middle barrier to the proximal barrier toform a second layer, a second end extends out of the groove in theproximal barrier; e. a second electrical wire wound on the bobbin, thesecond electrical wire having a first end retained by the proximalbarrier and extending over the windings of the first wire and retainedin the notch of the middle barrier and wound around the second windingarea of the cylindrical wall of the bobbin until the electrical wirereaches the distal barrier and then wound in the same direction butgoing from the distal barrier to the middle barrier, and then extendingover the first electrical wire with a second end extending through thegroove in the proximal barrier to rest adjacent to the first end of thesecond electrical wire; f. the bobbin movably retained in the housing sothat the hollow interior chamber of the bobbin surrounds the magnetassembly and the exterior wall and barriers of the bobbin reside withinthe gap in the housing between the magnet assembly and the interior wallof the housing, the central barrier of the bobbin being of sufficientwidth so that when windings on the bobbin are entirely within thehousing, the first electrical wire wound on the first winding area andthe second electrical wire wound on the second winding area do notencircle the middle permanent magnet and when the bobbin is in its fullyextended condition which is partially out of the housing, the firstelectrical wire wound on the first winding area and the secondelectrical wire wound on the second winding area do not encircle theproximal and distal permanent magnets; and g. a source of electricalcurrent connected to the first and second wires interacts with themagnetic fields created by the magnet assembly, thereby moving thebobbin axially relative to the housing so that the first and secondwindings are entirely within the housing in a first condition and thefirst winding is out of the housing while the second winding is in thehousing in a second condition.
 19. The linear motor in accordance withclaim 18 wherein the distal magnet, middle magnet and proximal magnetare each permanent magnets.
 20. The linear motor in accordance withclaim 18 wherein the distal pole piece, middle pole piece and proximalpole piece are each made of ferromagnetic material.
 21. The linear motorin accordance with claim 18 wherein the bobbin is affixed to an objectand the housing moves relative to the bobbin when the source ofelectrical current is applied to the wire.
 22. The linear motor inaccordance with claim 18 wherein the housing is affixed to an object andthe bobbin moves relative to the housing.
 23. The linear motor inaccordance with claim 18 wherein the proximal barrier further comprisesa transverse circular notch to retain the first and second end of thewire.
 24. The linear motor in accordance with claim 18 furthercomprising a multiplicity of windings of the wire in the first windingarea and the second winding area.